#include <iostream>
using namespace std;
static int some = []() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    return 0;
}();

class Solution
{
  public:
    /*
	Implement atoi to convert a string to an integer.

	Hint: Carefully consider all possible input cases. If you want a challenge, please do not see below and ask
	yourself what are the possible input cases.

	Notes: It is intended for this problem to be specified vaguely (ie, no given input specs). You are responsible
	to gather all the input requirements up front.

	Requirements for atoi:

	The function first discards as many whitespace characters as necessary until the first non-whitespace character is found.
	Then, starting from this character, takes an optional initial plus or minus sign followed by as many numerical digits
	as possible, and interprets them as a numerical value.

	The string can contain additional characters after those that form the integral number, which are ignored and have
	no effect on the behavior of this function.

	If the first sequence of non-whitespace characters in str is not a valid integral number, or if no such sequence
	exists because either str is empty or it contains only whitespace characters, no conversion is performed.

	If no valid conversion could be performed, a zero value is returned. If the correct value is out of the range
	of representable values, INT_MAX (2147483647) or INT_MIN (-2147483648) is returned.
	*/
    int myAtoi(string str)
    {
        if (str.empty())
            return 0;

        // trim
        auto offset = 0;
        while (str[offset] == ' ' || str[offset] == '0' && offset < str.length())
            offset++;

        auto sign = 1;
        // sign
        if (str[offset] == '-')
        {
            sign = -1;
            ++offset;
        }
        else if (str[offset] == '+')
        {
            sign = 1;
            ++offset;
        }

        auto ret = 0;
        for (auto i = offset; i < str.length(); ++i)
        {
            auto c = str[i];
            auto val = 0;
            if (c >= '0' && c <= '9')
                val = c - '0';
            else
                break;

            if (ret > INT_MAX / 10 || (ret == INT_MAX / 10 && val > 7))
                return sign > 0 ? INT_MAX : INT_MIN;

            ret *= 10;
            ret += val;
        }

        return sign * ret;
    }
};
